"We'll never have a situation where everyone supports an airport but I think we're moving to a situation where most people support an airport. I think in a democracy we've got to be mature about that," he said.

"The community has changed on this and if you don't support an airport please tell us how we're going to provide the jobs for the people in western Sydney that are travelling 30 hours a week in congested arterials.

"That's the key question. If you don't support the airport where are the jobs coming from? I can tell you they're not coming."

Both sides of politics say the airport would have to operate around the clock to attract the major airlines.

The Government says the first planes could be taking off well before 2027, though the airport would start small.

"We think planes could take off well within that time frame... however, clearly construction of an airport will take a long time. It will grow and expand," Mr Truss said.

"I think we all know that Sydney will need a second airport and they will need a second airport relatively soon."